app_sms: Ignore false positive stringop-overflow warning.

Ignore gcc warning about writing 32 bytes into a region of size 6,
since we check that we don't go out of bounds for each byte.

Resolves: asterisk#1088

Author: InterLinked1

apps/app_sms.c

@@ -467,7 +467,10 @@ static int packsms8(unsigned char *o, int udhl, unsigned char *udh, int udl, uns
 		if (u < 0 || u > 0xFF) {
 			return -1;                      /* not valid */
 		}
+#pragma GCC diagnostic push
+#pragma GCC diagnostic ignored "-Wstringop-overflow"
 		o[p++] = u;
+#pragma GCC diagnostic pop
 		if (p >= SMSLEN_8) {
 			return p;
 		}